Among the factors that affect SYSTEM 2000 performance are the size of the
database being accessed, the number of items being accessed, and the number of data records
qualified by the selection criteria. For databases that have many items and many data
records, you should evaluate all SAS programs that need to access the database directly.
In your evaluation, consider the following:
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Does the program need all the SYSTEM 2000 items? If not, create and use an appropriate
view descriptor that includes only the items that are needed.
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Do the selection criteria retrieve
only those data records needed for subsequent analysis? If not, specify
different conditions so that the selected records are restricted for
the program being used.
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Is the data going to be used by more than one procedure in one SAS
session? If it is, consider extracting the data and placing it in a
SAS data file for SAS procedures to use, instead of the data being accessed directly by each procedure.
See
Performance Considerations for circumstances when extracting
data is the more efficient method.
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Do the records need to be in a specific order? If they do, include a SYSTEM 2000
ordering-clause in the appropriate
view descriptors or an ORDER BY clause in a SAS program.
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Do the selection criteria enable SYSTEM 2000 to use
key (indexed) items and non-key (not indexed) items efficiently? See
where-clause in SYSTEM 2000 for guidelines for specifying efficient selection criteria.
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